MARTINEZ (CBS SF) — A Concord man whose pit bulls fatally mauled his 2-year-old step-grandson after leaving the boy and his 4-year-old brother unsupervised one morning four years ago was sentenced in a Martinez courtroom Monday to a year in jail and three years probation.

Steven Hayashi, 55, received the sentence during a hearing in Contra Costa County Superior Court this morning in connection with the fatal dog mauling of 2-year-old Jacob Bisbee.

Judge John Kennedy handed down the sentence Monday, three months after convicting Hayashi on charges of involuntary manslaughter and child endangerment. The defendant waived his right to a jury trial.

During the sentencing hearing Monday, several friends and relatives spoke in support of Hayashi and asked the judge for a lenient sentence.

But Knox said it was Hayashi’s negligence that led to his toddler step-grandson’s death the morning of July 22, 2010.

Jacob and his 4-year-old brother lived with their father along with Hayashi, Hayashi’s wife, and their two teenage sons at the defendant’s home on Trailcreek Court.

Jacob’s father had left the house for work around 5:30 a.m. and Hayashi left a couple of hours later with his son to play tennis, leaving the two young boys home with his wife, who was asleep, according to prosecutors.

Later that morning, Jacob and his brother wandered into the home’s garage where Hayashi kept three of his five pit bulls. The dogs attacked, ripping the toddler’s body apart.

Hayashi’s wife found the boy and called 911. Jacob was taken to John Muir Medical Center in Walnut Creek where he died from his injuries.

Knox said the blame lay on Hayashi, who was well aware that his dogs were dangerous but took no precautions to protect the children from them.

The defendant’s dogs were completely untrained, had to be kept outdoors, fought viciously with one another and had already killed two family pets, she said.

Jacob’s death was a tragedy that could have been avoided with basic precautions, Knox said.

“While there can never be justice or an appropriate punishment for leading to the death of your own family member, I hope this case reinforces for the public the very real dangers of maintaining dogs whose instinct is to chase and kill prey,” the prosecutor said.

David Cohen, Hayashi’s attorney, was not immediately available Monday for comment on his client’s sentence but has argued that there was no evidence Hayashi was responsible for the children at the time of Jacob’s death or that he knew the dogs were vicious.